Subtropical Storm Sean formed this morning between Bermuda and the Bahamas. Sean's formation brings this year's tally of named storms to eighteen, tying 2011 with 1969 as the 6th busiest Atlantic hurricane season since record keeping began in 1851. Only 2005, 1933, 1995, 1887, and 2010 have had more named storms. However, 2011 has had an unusually low percentage of its named storms reach hurricane strength. We've had an average number of hurricanes--six--meaning that only 33% of this year's named storms have made it to hurricane strength. Normally, 55 - 60% of all named storms intensify to hurricane strength in the Atlantic. There have been three major hurricanes in 2011, which is one above average, and the total Accumulated Cyclone Energy (ACE)--a measure of the destructive potential of this season's storms--has been about 20% above average. The rare combination of near-record ocean temperatures but unusually dry, stable air over the Atlantic is no doubt at least partially responsible for the unusually high count of named storms, but near-average number of hurricanes and ACE.

Figure 1. The subtropical disturbance that became Subtropical Storm Sean, as seen at 1 pm EST November 7, 2011. Image credit: NASA.

Infrared satellite loops reveal that Sean has developed a respectable amount of heavy thunderstorm activity near its center that is increasing in intensity and areal coverage. While the low-level circulation center is exposed to view, a band of thunderstorms is trying to wrap around and close of the center. If this occurs, more substantial strengthening can occur, since the center will be walled off from the dry air that is currently interfering with development. Bermuda radar shows weak rain bands from Sean rippling across the island, with the strongest rain showers well to the island's southwest. Sustained winds at the Bermuda airport have been under 30 mph this morning. Sustained winds near tropical storm force were occurring this morning at buoy 41048, about 300 miles west of Bermuda. Winds at the buoy were 38 mph, gusting to 47 mph at 6:50 am EST. Strong upper-level winds out of the west are creating about 20 knots of wind shear over Sean, which is low enough to allow some slow development. Sean is a relatively shallow storm, and the tops of its thunderstorms extend up only to about the 300 mb level. Normally, a tropical storm extends up to about 200 mb. The shallow nature of Sean's thunderstorms mean that the storm is less vulnerable to wind shear than normal, since the storm is not feeling the strongest winds aloft. Ocean temperatures are near 26.5°C (80°F), which is right at the boundary of being warm enough to support tropical storm formation.

Forecast for SeanSean will drift slowly west or northwest today and Wednesday. The latest SHIPS model forecast predicts wind shear will remain about where it is now through Thursday morning, which should allow Sean to slowly intensify to a 50 mph storm. If Sean can make the transition to a fully tropical storm, more significant intensification can occur. The computer models show little or no development of Sean, with none of our reliable models predicting it will become a hurricane. Bermuda is the only land area that need concern itself with Sean, as a trough of low pressure is expected to absorb the storm on Thursday and lift it quickly to the north or northeast. The center of Sean could pass close enough to Bermuda to bring the island heavy rain squalls and sustained winds of 40 - 45 mph on Thursday and Friday. NHC is giving a 28% chance that Bermuda will receive tropical storm-force winds of 39 mph. High wind shear should destroy Sean on Friday.

Figure 2. MODIS image of the hybrid low named "Rolf" in the Mediterranean Sea at 10:30 UTC November 8, 2011. Image credit: NASA.

Unusual tropical storm-like low forms off coast of FranceAn unusual hybrid low pressure system has formed in the Mediterranean Sea, about 100 miles south of the coast of France. The low began as an extratropical storm named "Rolf", but has stalled out over the relatively warm waters of the Mediterranean over the past two days, and has acquired tropical characteristics. Heavy thunderstorms have built over the northeast portion of the low, and the storm has a symmetric spiral shape with a cloud-free center, like a tropical storm. The Navy is calling this system Invest 99L. The National Hurricane Center is not responsible for the Mediterranean Sea, so they are not issuing any products for 99L. NOAA's Satellite and Information Service (NESDIS) is giving 99L a tropical classification based on its satellite presentation, with winds in the 40 - 45 mph range. French radar shows heavy rains from 99L are beginning to affect Southeast France and the island of Corsica. The Lion Buoy, located about 100 miles to the west of the center of 99L, recorded sustained winds of tropical storm force, 40 mph, at 00 UTC yesterday. Water temperatures at the buoy were 17°C (63°F), far below the 26°C threshold usually needed to sustain a tropical storm. The coldest waters I've seen a tropical storm form in were 22°C during Hurricane Epsilon of 2005. I doubt that NHC would name this system if they did have responsibility for the Mediterranean, due to the cold water temperatures.

"Rolf" is expected to move slowly northwards into the coast of South France by Wednesday night. Meteo France is predicting heavy rains of 30 - 40 mm/hr (1.2 - 1.6"/hr) will affect the coast Tuesday night through Wednesday, with sustained winds of 50 mph, gusting to 75 mph.

Figure 3. Hybrid subtropical storm of October 8, 1996, off the coast of Italy. According to Reale and Atlas (2001), the storm had characteristics similar to a hurricane, but formed over water of 21.5°C. "The maximum damage due to wind occurred over the Aeolian Islands, at 38.5°N, 15°E, to the northeast of Sicily: assistance for disaster relief was required. Unfortunately, no weather station data were available, but the media reported sheds, roofs and harbor devices destroyed, and houses and electric lines damaged, due to "extremely strong westerly wind." The perfect agreement between the observations at Ustica, the storm scale, the eye-like feature position and the damages over the Aeolian Island reasonably suggest that the hurricane-level intensity of 32 m/s (72 mph) was reached over the Aeolian Islands." A similar hybrid low affected Algeria on 9 - 10 November 2001. This storm produced upwards of 270 mm (10.6") of rain, winds of 33 m/s (74 mph), and killed 737 people near Algeirs, mostly from flooding and mud slides. Image credit: Dundee satellite receiving station.

According to research published by Gaertner et al. (2007), an increase in ocean temperatures of 3°C in the Mediterranean by the end of the century could lead to hurricanes forming there. Miguel Angel Gaertner of the University of Castilla-La Mancha in Toledo, Spain, ran 9 different climate models with resolutions of about 50 km and found that some (but not all) of the models simulated hurricanes in the Mediterranean in September by the end of the century, when ocean temperature could reach 30°C.

Though the Mediterranean may start seeing hurricanes by the end of the century, these storms should be rare and relatively short-lived for three reasons:

1) The Mediterranean is quite far north and is subject to strong wind shear from jet stream activity.

2) The waters are shallow, and have relatively low heat content. There is no deep warm water current like the Gulf Stream.

3) The Mediterranean has a lot of large islands and peninsulas poking into it, increasing the chances that a tropical storm would weaken when it encountered land.

ReferencesMeteo France has an interesting animation of the predicted winds and temperatures over the next few days.

Video 1. Reed Timmer video of the November 7, 2011 tornado in Tipton, OK. Here's another excellent video of the Tipton tornado and a tornado near Manitou, OK from Texas Storm Chasers. Storm chasing IS dangerous: one storm chaser had his vehicle overturned, but got into another vehicle and continued the chase.

Shaken and stirred: an earthquake and tornado for OklahomaIt was a rare multi-natural hazard day for Oklahoma yesterday, as the state experienced both a tornado and an earthquake, six hours apart. The damaging magnitude 5.6 earthquake that shook the state Saturday night spawned a magnitude 4.7 aftershock at 8:46 pm CST yesterday, 44 miles east of Oklahoma City. And at 2:47 pm CST, a tornado touched down in Southwest Oklahoma near Tipton. The tornado destroyed an Oklahoma State University agricultural office, and damaged a hay barn at a dairy farm. No injuries were reported. The UK MailOnline has an interesting article showing the radar image from Saturday's quake, which captured a massive groups of birds and insects that took flight after the ground shook.

This afternoon, NOAA's Storm Prediction Center has placed Southeast Oklahoma, East Texas, Southeast Missouri, and most of Arkansas in its "Slight Risk" area for severe weather, thanks to a strong low pressure system moving across the Plains. During the late afternoon, severe thunderstorms with high winds and large hail and expected over the region, and we cannot rule out an isolated tornado.

Bering Sea superstorm targets AlaskaA massive blizzard the National Weather Service is calling one of the most severe Bering Sea storms on record is gathering strength today to the west of Alaska. The storm is expected to "bomb" to a central pressure of 945 - 950 mb Tuesday night, and to 940 mb on Wednesday. These pressures, characteristic of a Category 3 hurricane, will be strong enough to generate sustained winds of Category 1 hurricane force over the waters to the west of Alaska, with winds of 50 - 70 mph expected along portions of the coast. Nome, Alaska is expecting a storm surge of 8 - 10 feet. Waves of 15 - 25 feet with ice on top will batter the shores, causing severe damage to the coast.

?? What are you talking about? I only posted info of tornado warnings and radar pics. I think you might have me confused with someone else on here. I've never trolled since I created my account. I think you maybe the troll and this is my last response to this on here as you will go on ignore.

Quoting Neapolitan:While the power's on, here's the downtown Nome webcam (it's on Front Street; the view is to the west-northwest up the coast). Yesterday it was overcast and relatively calm. Now this (may be intermittently interrupted):

While the power's on, here's the downtown Nome webcam (it's on Front Street; the view is to the west-northwest up the coast). Yesterday it was overcast and relatively calm. Now this (may be intermittently interrupted):

The system is likely to move north-northwestwards initially and then westwards towards Gulf of Aden during next 48 hrs and weaken gradually due to colder sea and interaction with land surface.

Satellite imagery indicates vortex over west central Arabian Sea near 15.0N 58.7E. Dvorak intensity is T2.0. Associated broken low/medium clouds with embedded intense to very intense convection seen over west Arabian sea between 12.0N to 21.5N and 56.0E to 61.0E. Minimum cloud top temperature is -78C. The convection has shown signs of disorganization during past 12 hours. The convection is sheared to north northeastward under the influence of the trough in westerlies at 200 HPA level.

3 minute sustained winds near the center is 30 knots with a central pressure of 1000 hPa. The state of the sea is rough to very rough around the center.

The Madden-Julian Oscillation index currently lies over Phase 6 with amplitude more than 1. As per the dynamical and statistical models, it would lie over the same phase during the next 2-3 days and then move to phase 7. the phase 6 and 7 are not favorable for intensification over the Arabian Sea. Sea surface temperature is 26-28C. The ocean heat content is less (<40kj/cm2) and not favorable for intensification. The relative vorticity at 850 HPA level and upper level divergence have not changed significantly in past 24 hours. The vertical wind shear of horizontal wind over the region is moderate to high. There is no significant 24 hours tendency of vertical wind shear around the system. Tropospheric ridge, which roughly runs along 17.0N. The convection due to the system shows sheared to the north northeast under the influence of the upper tropospheric westerly trough which roughly runs from 55.0N 70.0E to 17.0N 40.0E at 200 HPA. The convection also shows signs of disorganization during past 12 hours. Most of the models show intensification during next 12 hours then gradual weakening of the system thereafter.

Anyone interested in the Bering Sea Alaska Blizzacane(TM - my word) is welcome to visit my wunderblog, Alaska Super Storm aka To Nome: Love, bf to learn about the remote areas being hit or to post about the storm.

Quoting j2008:Anyone have info on if 1M made landfall, sure looks like it has.

In case anyone was still doubting it was subtropical, the fact that it weakened rapidly over land proves it. I have a feeling if that storm to its east was over water, it would also transition! Maybe Mediterranean storms are only so rare because there's so little water to work with?

There was a similar system over lake huron once. "hurricane huron". If i recall it just happened to stall over the small lake, then weakened rapidly upon landfall.

THREAT FOR ISOLATED DAMAGING WIND AND A TORNADO WILL PERSIST NEXT HOUR OR TWO FROM SRN THROUGH NERN LA AND EXTREME SWRN MS. OVERALL THREAT IS BECOMING INCREASINGLY MARGINAL.

LINE OF PRE-FRONTAL CONVECTION CONTINUES FROM S-CNTRL THROUGH NERN LA. A FEW OF THE STORMS STILL HAVE UPDRAFT ROTATION...BUT THE TREND HAS BEEN FOR ACTIVITY TO BECOME LESS ORGANIZED. AN ISOLATED TORNADO AND DAMAGING WIND GUST CANNOT BE RULED OUT DURING THE NEXT COUPLE OF HOURS. HOWEVER...DEEPER FORCING FOR ASCENT AND LLJ ARE LIFTING NORTH OF THE WARM SECTOR...AND STORMS ARE MOVING INTO AN INCREASINGLY MARGINAL THERMODYNAMIC ENVIRONMENT. THESE LIMITING FACTORS SUGGEST THE SEVERE THREAT WILL NOT LIKELY PERSIST BEYOND 07Z...AND ANOTHER WW ISSUANCE IS UNLIKELY.